JP2021147609A - Resin composition, printing ink using the same, and method for manufacturing printed matter - Google Patents

Abstract

To provide a resin composition and printing ink which enable production of a printed matter that is excellent in storage property and prevents occurrence of scumming, suppress mottling of a printed surface in long run printing of a waterless lithographic printing plate, enable production of a stable printed matter from initial printing to end, and are suitable for lithographic printing.SOLUTION: A resin composition contains a coloring material, (1) a resin having a hydrophilic group and (2) a wax having a hydrophilic group, and arbitrarily contains a solvent, and is used as printing ink.SELECTED DRAWING: None

Description

The present invention relates to a resin composition suitable as a printing ink, particularly an ink for lithographic printing, and a method for producing a printed matter.

From the viewpoint of dealing with environmental problems and preserving the working environment in recent years, efforts are underway to reduce the use of volatile petroleum solvents in various printing fields to reduce the use of volatile organic compounds (low VOC).

Planographic printing is a printing method that is widely used as a system for supplying printed matter at high speed, in large quantities, and at low cost, and is known as lithographic printing with water and lithographic printing without water.

In flat plate printing with water, the dampening water used in large quantities for image formation contains a large amount of volatile solvent, which poses a problem in terms of work and environment.

On the other hand, in waterless lithographic printing, silicone rubber or fluororesin is used for the non-image area, and no dampening water is required.

Since a large amount of petroleum-based solvent is also used in general lithographic printing ink, it is desired to make the ink water-based or solvent-free. In addition, since a large amount of petroleum-based solvent is used as a cleaning agent for inks used in the printing process, the development of printing inks that can use water-based cleaning agents that do not contain volatile solvents is progressing. Has been done.

Patent Document 1 discloses a lithographic printing ink that can be washed with water without a solvent.

On the other hand, lithographic printing inks are required to suppress scratches that occur when the printed surface overlaps the back surface of the printed matter. In addition, it has been pointed out that when a large amount of printed matter is left in layers, the printed surface and the back surface stick to each other, which is a so-called blocking problem. In order to deal with such a problem, waxes such as polytetrafluoroethylene fine particles and polyethylene fine particles are dispersed in the ink (Patent Documents 2 to 4).

International Publication No. 2017-047817 (Detailed description of the invention) Japanese Patent Application Laid-Open No. 8-113748 (Claims) JP-A-2005-105049 (Claims) JP-A-2018-2956 (Claims)

However, the conventional lithographic printing ink containing resin and wax has a problem that the wax separates and the storage stability is poor when left for a long period of time. When the ink containing the separated wax is used, the separated wax adheres to the silicone rubber which is the non-image area of the waterless lithographic printing plate, and the ink is printed on the white background of the printed matter. It causes so-called ground pollution. Furthermore, when long-run printing is performed using waterless lithographic printing, the wax separated on the image area of the printing plate, the blanket of the printing machine, and the ink roller gradually accumulates, and the printed surface becomes white in the printed matter. There was a problem that printing defects were generated.

In the present invention, the above-mentioned problems, that is, problems caused by poor storage stability in lithographic printing inks, are coloring materials, (1) resins having hydrophilic groups, and (2) waxes having hydrophilic groups. Further, the purpose is to prepare a resin composition optionally containing a solvent, and to prepare a printing ink composed of the resin composition. The present invention also proposes many improvements.

According to the present invention, it is possible to obtain a printed matter having excellent storage stability and no background stains, and further, the mottling of the printed surface in long-run printing of a waterless lithographic printing plate is suppressed, and the printed matter is stable from the beginning to the end of printing. Printed matter can be obtained.

Hereinafter, the present invention will be specifically described.

The resin composition of the present invention contains a coloring material. When this coloring material is used as a printing ink, it is expected to give characters, figures or colors to the printed matter. As the coloring material used in the present invention, when an electromagnetic wave including the case of light is irradiated (input), an electromagnetic wave having a spectrum different from that of the electromagnetic wave is returned to the receiver including the case of a receiver (output). ) Any pigment can be used. The input electromagnetic wave and the output electromagnetic wave are not limited to visible light, and the present invention also includes a material that outputs visible light to ultraviolet rays and a material that outputs ultraviolet rays to X-rays. Corresponds to the color material referred to in. Typically, there is a material that absorbs all or part of the wavelength of white light and returns the rest of the light, so that where the colorant is present appears to be colored. Further, if the place where the color material is present and the place where the color material is not present can be distinguished in the printed matter, the case where the colored material is transparent is also included.

The lithographic printing ink according to the present invention can be used as a clear ink containing no pigment. Further, by containing a pigment, it can be used as a multicolor ink such as ink, safflower, indigo, and yellow ink.

In the coloring material used in the present invention, as pigments, for example, titanium dioxide, calcium carbonate, barium sulfate, red iron oxide, cadmium red, chrome yellow, zinc yellow, dark blue, ultramarine blue, organic bentonite, alumina white, iron oxide, carbon black, etc. Examples include graphite and aluminum.

Examples of organic pigments include phthalocyanine pigments, soluble azo pigments, insoluble azo pigments, azolake pigments, quinacridone pigments, isoindolin pigments, slen pigments, metal complex pigments, and the like, and specific examples thereof include phthalocyanine. Examples thereof include blue, phthalocyanine green, azo red, mono azo red, mono azo yellow, disazo red, disazo yellow, quinacridone red, quinacridone magenta, and isoindrin yellow.

These pigments can be used alone or in admixture of two or more.

The concentration of the coloring material contained in the resin composition of the present invention is not particularly limited, but at the time of use as an ink, it is preferably 5% by mass or more in order to obtain a required printing paper surface concentration, and 10% by mass. More preferably, it is more preferably 15% by mass or more. Further, since the fluidity of the ink is good, the content is preferably 40% by mass or less, more preferably 30% by mass or less, and further preferably 25% by mass or less.

The resin composition of the present invention contains (1) a resin having a hydrophilic group. (1) When a resin composition containing a resin having a hydrophilic group is used as a printing ink, particularly a lithographic printing ink, it becomes soluble in a water-based cleaning liquid containing water as a main component, and a non-petroleum-based cleaning agent can be applied. Is. Further, since the hydrophilic group interacts with the surface functional group of the wax in the ink, it can also have good wax dispersibility. In addition, the hydrogen bonds between the hydrophilic groups improve the viscosity characteristics of the ink, which also contributes to the improvement of ground stain resistance during lithographic printing. As a result of the ink adhering to the non-image area of the lithographic printing plate, the ink is also transferred onto the printed matter.

(1) In the resin having a hydrophilic group, the hydrophilic group means a functional group having a property of having a high affinity for water, and a specific example of such a hydrophilic group is dissolution in water. From the viewpoint of properties, it is preferable that it is an acidic group such as a carboxyl group, a sulfo group, a phosphoric acid group, or a hydroxyl group, and it is possible to achieve both good dispersibility of wax and pigment and solubility in water. Groups are particularly preferred.

The acid value of the resin having the hydrophilic group (1) used in the present invention is preferably 100 mgKOH / g or more and 250 mgKOH / g or less. The acid value of the resin having the (1) hydrophilic group is more advantageous in terms of improving the dispersibility of the wax and the stain resistance, and 100 mgKOH in order to obtain good solubility of the resin in an aqueous cleaning solution. It is preferably / g or more, and more preferably 150 mgKOH / g or more. Further, when the acid value is large, the interaction between the resins becomes large and the dispersibility of the wax decreases. Therefore, it is preferably 250 mgKOH / g or less, and more preferably 200 mgKOH / g or less.

The acid value of the resin having a hydrophilic group and the acid value of the wax having a hydrophilic group, which will be described later, are determined by the neutralization titration method according to the test method Section 3.1 of JIS K 0070: 1992. Can be obtained in accordance with.

(1) Specific examples of the resin having a hydrophilic group include acrylic resin, styrene acrylic resin, styrene maleic acid resin, rosin-modified maleic acid resin, rosin-modified acrylic resin, epoxy resin, water-soluble polyester resin, and water-soluble nylon. Examples thereof include water-soluble polyurethane resin, phenol resin, polyvinyl alcohol and the like.

Among the resins listed above, acrylic resins, styrene acrylic resins, and styrene maleic acid resins are available from the viewpoints of ease of obtaining monomers, low cost, ease of synthesis, compatibility with ink and other components, and dispersibility of pigments. However, (1) it is preferably used as a resin having a hydrophilic group.

(1) Among the resins having a hydrophilic group, the acrylic resin, the styrene acrylic acid resin, and the styrene maleic acid resin can be produced by the following methods. That is, carboxyl group-containing monomers such as acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, vinyl acetate or their acid anhydrides, hydroxyl group-containing monomers such as 2-hydroxyethyl acrylate, and dimethylaminoethyl methacrylate. Amino group-containing monomers such as, mercapto group-containing monomers such as 2- (mercaptoacetoxy) ethyl acrylate, sulfo group-containing monomers such as acrylamide t-butyl sulfonic acid, and phosphoric acids such as 2-methacryloxyethyl acid phosphate. A compound selected from a group-containing monomer, methacrylic acid ester, acrylic acid ester, styrene, acrylonitrile, vinyl acetate and the like is polymerized or copolymerized using a radical polymerization initiator.

(1) Preferred specific examples of the resin having a hydrophilic group are obtained from a monomer composition containing (a) styrenes, (b) (meth) acrylic acid alkyl ester and (c) a hydrophilic group-containing vinyl monomer. Examples of the copolymer are (a) resins having a styrene content of 40% by mass or more and 60% by mass or less.

Examples of the styrenes include styrene, α-methylstyrene, and styrene compounds having at least one alkyl group having 1 to 4 carbon atoms in the aromatic ring, as compounds having a styrene skeleton. A lithographic printing ink containing (1) a resin having a hydrophilic group copolymerized with styrenes can provide a printed matter having excellent wear resistance due to its elasticity derived from the aromatic ring skeleton. (1) By setting the content of (a) styrenes of the resin having a hydrophilic group to 40% by mass or more, the elasticity is improved, the ground stain resistance is lowered, and the abrasion resistance of the printed matter is further improved. be able to. Further, when the content of (a) styrenes is 60% by mass or less, the solubility in the ethylenically unsaturated compound can be ensured, the viscosity of the ink can be suppressed, and the dispersibility of the wax becomes good. It is possible to obtain an ink in which the problem of not being able to obtain an appropriate print density caused by the low dispersibility of the wax and the problem of resin precipitation during storage of the ink are further suppressed. (1) The styrenes (a) contained in the resin having a hydrophilic group are preferably contained in an amount of 45% by mass or more, and preferably 55% by mass or less.

(1) The content of (a) styrenes contained in the resin having a hydrophilic group can be measured by NMR analysis after eluting the resin from the lithographic printing ink using gel permeation chromatography (GPC). can.

Further, (1) a resin having a hydrophilic group in which an ethylene unsaturated group is added by reacting, for example, glycidyl (meth) acrylate with a part of the hydrophilic group of the resin having a hydrophilic group may be used.

Examples of the (b) (meth) acrylic acid alkyl ester include methyl acrylate, methyl methacrylate, ethyl acrylate, and ethyl methacrylate as the alkyl ester of acrylic acid or methacrylic acid.

Further, as the (c) hydrophilic group-containing vinyl monomer, examples of the monomer containing both a hydrophilic group and a vinyl group include acrylic acid, methacrylic acid, vinyl alcohol and the like.

The weight average molecular weight of the resin having the (1) hydrophilic group is preferably 5,000 or more, and more preferably 15,000 or more in order to obtain the water resistance of the cured film. Further, in order to obtain water solubility of the resin, it is preferably 100,000 or less, and more preferably 50,000 or less.

The weight average molecular weight can be determined by measuring in terms of polystyrene using gel permeation chromatography (GPC).

The content of (1) the resin having a hydrophilic group contained in the resin composition of the present invention is the viscosity of the ink required for printing and the sensitivity required for curing when the mass of the resin composition is 100% by mass. It is preferably 5% by mass or more, and more preferably 10% by mass or more because it is easy to obtain. Further, since it is easy to obtain the fluidity of the ink required for printing and the transferability between the rollers, (1) the content of the resin having a hydrophilic group is preferably 60% by mass or less, preferably 50% by mass or less. Is more preferable, and 40% by mass or less is further preferable.

The resin composition of the present invention contains (2) a wax having a hydrophilic group.

(2) Wax having a hydrophilic group forms a hydrogen bond with (1) a resin having a hydrophilic group and exhibits good dispersibility. Therefore, even if the ink is stored for a long period of time, the wax does not separate.

Examples of waxes include natural waxes such as paraffin, microcrystalin, petrolatam, monttan, beeswax and carnauba, semi-synthetic waxes such as fatty acid amide and fatty acid ester, and synthetic waxes such as Fishertropus, low density polyethylene, high density polyethylene and polypropylene. Be done. The addition of hydrophilic groups to the wax includes, for example, oxidation treatment of the wax.

In the present invention, (2) a wax having a hydrophilic group does not correspond to (1) a resin having a hydrophilic group.

(2) The hydrophilic group of the wax having a hydrophilic group has the same meaning as the hydrophilic group described for (1) the resin having a hydrophilic group, and specific examples thereof include a carboxyl group and a sulfo group. , Phosphoric acid group, hydroxyl group and the like, and among these, the carboxyl group is preferable because it easily forms a hydrogen bond with the resin having (1) a hydrophilic group.

(2) The acid value of the wax having a hydrophilic group is preferably 2 mgKOH / g or more. By setting the content to 10 mgKOH / g or more and 100 mgKOH / g or less, (1) the hydrogen bond with the resin having a hydrophilic group can be further strengthened, and good dispersibility is exhibited in long-term storage. Further, by setting the acid value to 20 mgKOH / g or more and 50 mgKOH / g or less, the occurrence of mottling can be further suppressed even when a large amount of printing is performed.

The average particle size of (2) the wax having a hydrophilic group contained in the resin composition of the present invention is preferably 0.5 micron or more and 10 microns or less, and the particle shape is scaly, amorphous, or spherical. Either of them may be used. Waxes with different shapes may be used.

Since the content of (2) the wax having a hydrophilic group contained in the resin composition of the present invention effectively imparts abrasion resistance to the printed film and suppresses blocking, the mass of the resin composition is 100. In terms of mass%, it is preferably 0.1% by mass or more, and more preferably 0.2% by mass or more. Further, in order to obtain a printed matter having high gloss, 5% by mass or less is preferable, and 2% by mass or less is more preferable, from the viewpoint of further suppressing the occurrence of mottling.

In addition, the resin composition of the present invention may optionally contain a solvent. The solvent can be appropriately selected according to the desired properties, properties, and purpose, such as adjusting the fluidity of the resin composition and dispersing and stabilizing the coloring material, and a conventionally known solvent can be used. In consideration of the environmental load, it is preferable to use no solvent when it can be used.

When the resin composition of the present invention is used as an active energy ray-curable lithographic printing ink, it is preferable, and (3) a compound having an ethylenically unsaturated group can be contained.

(3) The compound having an ethylenically unsaturated group is a compound that polymerizes by a radical generated from a photopolymerization initiator described later or by irradiating with an electron beam to increase the molecular weight (hereinafter, simply "monomer"). (Called).

The monomer has an ethylenically unsaturated group and is a component that polymerizes to increase the molecular weight as described above, but in the state before polymerization, it is often a liquid component having a relatively low molecular weight, (1). It is also used as a solvent for dissolving a resin having a hydrophilic group to form a varnish, and for adjusting the viscosity of an ink composition. Examples of the monomer include a monofunctional monomer having one ethylenically unsaturated group in the molecule and a bifunctional or higher monomer having two or more ethylenically unsaturated groups in the molecule. Bifunctional or higher functional monomers are preferably used because they can crosslink molecules with each other when the ink is cured, thus increasing the curing rate and forming a strong film.

Assuming that the compound is used as an active energy ray-curable slab printing ink, the content of the compound having an ethylenically unsaturated group contained in the resin composition of the present invention is 100% by mass based on the mass of the resin composition. When it is, it is preferably 30 to 90% by mass, and more preferably 40 to 85% by mass. When the content of the compound having an ethylenically unsaturated group is in the above range, both good curability and printability can be achieved.

Assuming that the resin composition of the present invention is used as an active energy ray-curable lithographic printing ink, the resin composition of the present invention preferably contains a photopolymerization initiator in order to improve the sensitivity. In addition, a sensitizer may be included to assist the effect of the photopolymerization initiator. There are mechanically different types of such photopolymerization initiators, such as a single molecule system direct cleavage type, an ion pair electron transfer type, a hydrogen abstraction type, and a two molecule complex system, and they can be selected and used.

The photopolymerization initiator used in the present invention is preferably one that generates an active radical species, and specific examples thereof include 4,4-bis (dimethylamino) benzophenone (also known as Michler ketone), α-hydroxyacetophenone, and α. -Aminoacetophenone, acylphosphine oxide, titanocene, o-acyloximes 2-methyl- [4- (methylthio) phenyl] -2-morpholino-1-propan-1-one, 2-benzyl-2-dimethylamino- Examples thereof include 1- (4-morpholinophenyl) -butanone, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenyl-phosphine oxide and the like. Specific examples of the sensitizer include 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone, 4,4-bis (diethylamino) -benzophenone, 4,4-bis (dimethylamino) chalcone, and p-dimethylaminocinna. Examples thereof include millidenindanone, 1,3-bis (4-dimethylaminobenzal) acetone, N-phenyl-N-ethylethanolamine, ethyl diethylaminobenzoate, 3-phenyl-5-benzoylthiotetrazole and the like. Each of these photopolymerization initiators and sensitizers may be used alone, but each of them may be used in two or more kinds.

Since good sensitivity can be obtained when the active energy ray-curable lithographic printing ink is used, the content of the photopolymerization initiator is 0.1% by mass or more when the mass of the resin composition is 100% by mass. Is preferable, 1% by mass or more is more preferable, and 3% by mass or more is further preferable. Further, since the storage stability of the active energy ray-curable flat plate printing ink is improved, the content of the photopolymerization initiator is 20% by mass or less when the mass of the resin composition is 100% by mass. Is preferable, 15% by mass or less is more preferable, and 10% by mass or less is further preferable. Further, when the sensitizer is contained, the content thereof is good when the active energy ray-curable lithographic printing ink is used. Therefore, when the mass of the resin composition is 100% by mass, 0.1% by mass or more is preferable, 1% by mass or more is more preferable, and 3% by mass or more is further preferable. Further, since the storage stability of the active energy ray-curable lithographic printing ink is improved, the content of the sensitizer is preferably 20% by mass or less when the mass of the resin composition is 100% by mass. , 15% by mass or less is more preferable, and 10% by mass or less is further preferable.

As the active energy rays that can be used, any one that has the excitation energy required for the curing reaction can be used, but for example, ultraviolet rays and electron beams are preferably used. When curing with an electron beam, an electron beam device having an energy ray of 100 to 500 eV is preferably used. When curing by ultraviolet rays, an ultraviolet irradiation device such as a high-pressure mercury lamp, a xenon lamp, a metal halide lamp, or an LED is preferably used. For example, when a metal halide lamp is used, it is conveyed by a conveyor by a lamp having an illuminance of 80 to 150 W / cm. Curing at a speed of 50 to 150 m / min is preferable from the viewpoint of productivity.

In the resin composition of the present invention, additives such as extender pigments, pigment dispersants, antifoaming agents, and transferability improvers can be used as needed.

Next, a manufacturing method when the resin composition of the present invention is manufactured as a lithographic printing ink will be specifically described. However, the present invention is not construed as being limited to such an example.

Flat plate printing ink is a kneader, a three-roll mill, a ball mill, a planetary ball mill, and a bead mill, together with a coloring material, a resin having a hydrophilic group, a wax having a hydrophilic group, a compound having an ethylene unsaturated group, an additive, and other components. , Roll mill, attritor, sand mill, gate mixer, paint shaker, homogenizer, self-revolving stirrer, etc. It is obtained by uniformly mixing and dispersing with a stirrer / kneader. Defoaming under vacuum or reduced pressure conditions is also preferably performed after mixing and dispersing, or in the process of mixing and dispersing.

Further, the method for producing the printed matter when the active energy ray-curable lithographic printing ink is used can be, for example, as follows. First, a lithographic printing ink is applied onto a printed matter, and then the printed matter is cured by irradiating it with active energy rays to obtain a printed matter having an ink-cured film. Examples of the printed matter include, but are not limited to, art paper, coated paper, cast paper, synthetic paper, newspaper, aluminum-deposited paper, metal, polypropylene, polyethylene terephthalate, and the like.

Further, as a method of applying ink on a printed matter when the resin composition of the present invention is used as a printing ink, a method of directly applying the ink to the printed matter or a method of indirectly applying the ink to the printed matter, for example, once. Examples thereof include a step of applying to a transfer plate to form an image and a method of imparting an image formed on the transfer plate by a step of transferring the image onto a printed matter. Specifically, it can be applied onto a printed matter by a well-known method such as flexographic printing, offset printing, gravure printing, screen printing, and bar coater.

As a printing method, it is preferable to adopt a lithographic printing method. There are two methods for lithographic printing, one with water and the other without water, but either method can be used.

If the resin composition of the present invention is used as an ink, a conventionally used cleaning liquid containing an organic solvent as a main component can be used in a printing apparatus, but cleaning with a cleaning liquid containing water as a main component can be used. It is also possible to do. As the cleaning solution containing water as a main component, for example, an aqueous cleaning solution adjusted to pH 8 to pH 13 using an inorganic base or amino acid can be used. Specific examples of the inorganic base include alkali metal carbonates such as lithium carbonate, sodium carbonate and potassium carbonate, alkali metal bicarbonates such as lithium hydrogen carbonate, sodium hydrogen carbonate and potassium hydrogen carbonate, and disodium hydrogen phosphate. Examples thereof include potassium hydroxide such as lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, tetramethylammonium hydroxide and tetraethylammonium hydroxide.

Hereinafter, the present invention will be specifically described with reference to Examples. However, the present invention is not construed as being limited to these specific examples.

<(1) Production of resin having a hydrophilic group>
A reaction vessel equipped with a stirrer, a reflux cooling tube, a thermometer and a nitrogen gas introduction tube was charged with 150 parts by mass of propylene glycol monomethyl ether acetate, 50 parts by mass of styrene, 19 parts by mass of ethyl acrylate and 31 parts by mass of acrylic acid as solvents. 4 parts by mass of 2,2'-azobis (2-methylbutyronitrile) was added as a polymerization initiator. A dropping polymerization reaction was carried out at 140 ° C. for 1.5 hours with reflux and stirring, and the mixture was kept warm for 1 hour. Then, the temperature was raised to 160 ° C., the solvent was distilled off while continuing stirring at normal pressure, then the pressure was reduced to 50 mmHg or less at the same temperature, the solvent was completely distilled off, and the weight average molecular weight (hereinafter, Mw) 19 A resin 1 having an acid value of 186 mgKOH / g was obtained. The results are shown in Table 1. The weight average molecular weight of the resin is a value measured by GPC. GPC is HLC-8220 (manufactured by Tosoh Co., Ltd.), columns are TSKgel SuperHM-H (manufactured by Tosoh Co., Ltd.), TSKgel SuperHM-H (manufactured by Tosoh Co., Ltd.), TSKgel SuperH2000 (manufactured by Tosoh Co., Ltd.) in that order. The one linked with the above was used, tetrahydrofuran was used as a mobile phase, and RI detection was measured using the RI detector built in the GPC. A calibration curve was prepared using a polystyrene standard material, and the weight average molecular weight of the resin was calculated. The measurement sample is diluted with tetrahydrofuran so that the resin concentration becomes 0.25% by mass, and the diluted solution is dissolved by stirring with a mix rotor (MIX-ROTAR VMR-5, manufactured by AS ONE Co., Ltd.) at 100 rpm for 5 minutes. The mixture was obtained by filtering with a 0.2 μm filter (Z227536-100EA, manufactured by SIGMA). The measurement conditions were a driving amount of 10 μL, an analysis time of 30 minutes, a flow rate of 0.4 mL / min, and a column temperature of 40 degrees.

Description of abbreviations in Table 1 ST: Styrene EA: Ethyl acrylate AA: Acrylic acid.

<Manufacturing of resins 2 to 5 having a hydrophilic group and resin 6 having no hydrophilic group>
Resins 2 to 5 having hydrophilic groups and resins having no hydrophilic groups in the same manner as resin 1 except that the amounts of styrene, ethyl acrylate, and acrylic acid charged were changed as shown in Table 1. I got 6. Table 1 shows the resin composition and the resin physical characteristics.

<Ink raw material>
Resin having a hydrophilic group: Resins 1 to 5
Resin without hydrophilic group: Resin 6
Wax: As shown in Table 2 and:
Wax 1 (wax having a hydrophilic group): Montan wax having an acid value of 15 mg_KOH / g having a carboxyl group, "CERIDUST" (registered trademark) 5551 (manufactured by Client Chemicals Co., Ltd.)
Wax 2 (wax having a hydrophilic group): Highly modified hydrocarbon wax having a carboxyl group and an acid value of 85 mg_KOH / g, "CERIDUST" (registered trademark) 8020 (manufactured by Client Chemicals Co., Ltd.)
Wax 3 (wax having a hydrophilic group): Polyethylene oxide wax having an acid value of 4 mg_KOH / g having a carboxyl group, "CERIDUST" (registered trademark) 3715 (manufactured by Client Chemicals Co., Ltd.)
Wax 4 (wax without hydrophilic group): Polyethylene wax with an acid value of 0 mg_KOH / g, "CERIDUST" (registered trademark) 3620 (manufactured by Client Chemicals Co., Ltd.)
Wax 5 (wax having a hydrophilic group): Fischer-Tropsch wax having a carboxyl group and an acid value of 28 mg_KOH / g, "Sasolwax" (registered trademark) A28 (manufactured by Sasol Performance Chemicals Co., Ltd.).

The wax 5 had an average particle size of 5 μm using a jet mill.

Pigment: Carbon black, "MOGUL" (registered trademark) E (manufactured by CABOT)
Photopolymerization Initiator: "Irgacure" (registered trademark) 907 (manufactured by BASF) "Irgacure" (registered trademark) TPO-L (manufactured by BASF)
Sensitizer: Diethylaminobenzophenone (manufactured by Tokyo Kasei Co., Ltd.)
Compound with ethylenically unsaturated group: Pentaerythritol tetraacrylate ethylene oxide adduct "Miramer" (registered trademark) M4004 (manufactured by MIWON)
Constituent pigment: "Micro Ace" (registered trademark) P-3 (manufactured by Nippon Tarku Co., Ltd.)
Pigment dispersant: "Disparon" (registered trademark) DA-325 (manufactured by Kusumoto Kasei Co., Ltd.).

<Manufacturing of lithographic printing ink>
As shown in Table 3, weigh the resin, wax, pigment, photopolymerization initiator, sensitizer, monomer, extender pigment and pigment dispersant, and weigh the three roll mill "EXAKT" (registered trademark) M-80S (EXAKT). The roller gap scale was set to 1 and the roll rotation speed scale was set to 500 rpm, and the mixture was kneaded four times to obtain flat plate printing inks (inks 1 to 10).

<Waterless lithographic printing test>
A waterless lithographic printing plate (TAN-E, manufactured by Toray Co., Ltd.) is mounted on an offset printing machine (Oliver 266EPZ, manufactured by Sakurai Graphic Systems Co., Ltd.), and each ink manufactured is used to print on 5000 sheets of coated paper. Using an ultraviolet irradiation device (120 W / cm, one ultra-high pressure metahara lamp) manufactured by USHIO Co., Ltd., ultraviolet rays were irradiated at a belt conveyor speed of 80 m / min to cure the ink, and a printed matter was obtained. Each evaluation method is as follows.

<Ink evaluation method>
(1) Ink storage stability The ink was stored in a container at a temperature of 30 ° C. for 3 months and 6 months in a sealed state. The ink after storage was visually observed, and the case where the wax was not separated was evaluated as A, and the case where the wax was separated was evaluated as B.

(2) Ground stain resistance Printing was performed using ink that had been stored for 6 months in an environment with a temperature of 30 ° C. When the solid area black density of the printed matter was 1.8, the black color density in the non-image area of the printed matter was evaluated using a reflection densitometer (SpectroEye manufactured by GretagMacbeth) under the conditions of printing temperatures of 25 ° C. and 30 ° C. .. When the reflection density exceeds 0.10, the ground stain resistance is poor and is evaluated as B, and when it is 0.10 or less, the ground stain resistance is good and is evaluated as A and is 0.05 or less. The ground stain resistance was extremely good, and it was evaluated as AA.

(3) Mottling resistance Using ink that has been stored for 6 months in an environment with a temperature of 30 ° C, adjust the printing machine so that the solid ink density of the printed matter is 1.8 and the printing temperature is 25 ° C, 5000. Printing was performed on 10000 sheets and 10000 sheets. The solid part printed at the initial stage and after printing 5000 sheets is visually observed and evaluated as A when printed at a uniform density, and the solid part printed at the initial stage and after printing 10000 sheets is visually observed and printed at a uniform density. The case where there was a white spot was evaluated as AA, and the case where there was a white spot in the black solid part after printing 5000 sheets was evaluated as B.

[Example 1]
Using ink 1, the ink storage stability, ground stain resistance, and mottling resistance were evaluated by the above-mentioned methods. The results are shown in Table 4.

The lithographic printing ink produced had extremely good ground stain resistance at both printing temperatures of 25 ° C. and 30 ° C. The mottling resistance was good.

[Examples 2 to 8, Comparative Examples 1 and 2]
The evaluation was carried out in the same manner as in Example 1 except that the inks shown in Table 4 were used. The results are shown in Table 4. The ink of Example 2 was excellent in storage stability for 6 months, and the ground stain resistance was extremely good at both printing temperatures of 25 ° C. and 30 ° C. The mottling resistance was good. The ink of Example 3 had a good storage period of 3 months, but was insufficient for 6 months. The ground stain resistance was extremely good at a printing temperature of 25 ° C., and was good at a printing temperature of 30 ° C. The mottling resistance was good. The inks of Examples 4 and 5 were good for a storage period of 3 months, but insufficient for a storage period of 6 months. The ground stain resistance was extremely good at a printing temperature of 25 ° C., and was good at a printing temperature of 30 ° C. The mottling resistance was good. The ink of Example 6 was excellent in storage for 6 months, and the ground stain resistance was good at both printing temperatures of 25 ° C. and 30 ° C. The mottling resistance was good. The ink of Example 7 had a good storage period of 3 months, but was insufficient for 6 months. The ground stain resistance was extremely good at a printing temperature of 25 ° C., and was good at a printing temperature of 30 ° C. The mottling resistance was good. The ink of Example 8 was excellent in storage stability for 6 months, and the ground stain resistance was extremely good at both printing temperatures of 25 ° C. and 30 ° C. The mottling resistance was extremely good.

The inks of Comparative Example 1 and Comparative Example 2 had insufficient storage stability, and had insufficient ground stain resistance and mottling resistance.

After the printing evaluation of the lithographic printing inks of Examples 1 to 8, the roller cleaning of the printing machine was performed using a cleaning solution containing water as a main component adjusted to pH 11 with an amino acid (L-arginine), and the ink was removed. We were able to.

Claims (8)

A resin composition containing a coloring material, (1) a resin having a hydrophilic group, and (2) a wax having a hydrophilic group, and optionally a solvent. (2) The resin composition according to claim 1, wherein the hydrophilic group of the wax having a hydrophilic group is a carboxyl group. (2) The resin composition according to claim 1 or 2, wherein the wax having a hydrophilic group has an acid value of 10 mgKOH / g or more and 100 mgKOH / g or less. (1) The resin composition according to any one of claims 1 to 3, wherein the acid value of the resin having a hydrophilic group is 100 mgKOH / g or more and 250 mgKOH / g or less. The resin having the (1) hydrophilic group is a copolymer of (a) styrenes, (b) (meth) acrylic acid alkyl ester and (c) a monomer containing a hydrophilic group-containing vinyl monomer, and the above-mentioned resin. When the mass of the copolymer is 100% by mass, any of claims 1 to 4 in which the content of the structural portion derived from (a) styrene contained in the copolymer is 40% by mass or more and 60% by mass or less. The resin composition described in Crab. A printing ink comprising the resin composition according to any one of claims 1 to 5. A printed matter in which the printing ink according to claim 6 is adhered to a printed matter. A method for producing a printed matter, which comprises a step of applying the printing ink according to claim 6 to a transfer plate to form an image, and a step of transferring the image formed on the transfer plate onto a printed matter.